The present invention relates to a method and apparatus for use when inserting a bar of metal into a crucible. In particular, the present invention relates to a method of reducing the production of chips of refractory material as a metal bar is inserted into a receptacle formed of a refractory material.
Melting of high temperature nickel or cobalt base alloys in a vacuum furnace requires the use of a refractory crucible to contain the molten metal. A bar of metal having the desired composition is inserted into the crucible either manually or by using a machine. During the process of inserting the bar of metal into the crucible, chips of refractory material may be produced. These chips may be produced either by sliding, abrasive contact between the leading end portion of the bar and the side of the crucible or by shock to the crucible when the leading end portion of the bar reaches the bottom of the crucible. The chips of refractory material are undesirable because they become suspended in the molten metal, enter a mold cavity, and ultimately form detrimental inclusions in an otherwise acceptable casting.